Steps to reproduce the issue

• Enter TinyMCE plugin settings and disable iframe / script tag filtering, or enable use Joomla text filter option.
• Add content to a page which contains an iframe or script tag
• Switch between editor and HTML modes or attempt to save the page.

Expected result

Page is saved correctly and iframe / script tags are preserved.

Actual result

Iframe/script tags are stripped by the editor and cannot be saved. Adding iframes or script tags is only possible when the TinyMCE plugin is disabled entirely.

System information (as much as possible)

Joomla 4.0.2 using Docker-compose on Ubuntu.

Additional comments

Even with Joomla system wide content filtering disabled, as well as the "Use Joomla text filter" option enabled, TinyMCE strips protected tags from the HTML and ignores this configuration.